Sizing composition for mineral wool based on hydrogenated sugar and insulating products obtained

ABSTRACT

A sizing composition for insulating products based on mineral wool, in particular of glass or of rock, which includes at least one hydrogenated sugar and at least one polyfunctional crosslinking agent. Another subject matter of the present invention is the insulating products based on mineral fibers thus obtained.

The present invention relates to the field of thermal and/or acousticinsulating products based on mineral wool, in particular of glass or ofrock, and on a formaldehyde-free organic binder.

The invention more particularly relates to a sizing composition capableof crosslinking thermally to form said organic binder, which includes atleast one hydrogenated sugar and at least one polyfunctionalcrosslinking agent, and to the insulating products which resulttherefrom.

The manufacture of insulating products based on mineral wool generallycomprises a stage of manufacture of the wool itself, which can becarried out by various processes, for example according to the knowntechnique of fiberizing by internal or external centrifugation.

Internal centrifugation consists in introducing the molten mineralmaterial (glass or rock) into a centrifugal device comprising amultitude of small orifices, the material being projected towards theperipheral wall of the device under the action of the centrifugal forceand escaping therefrom in the form of filaments. On leaving thecentrifugal device, the filaments are drawn and carried toward areceiving member by a gas stream having a high temperature and a highspeed, in order to form a web of fibers (or mineral wool).

External centrifugation consists, for its part, in pouring out themolten material at the external peripheral surface of rotating members,known as rotors, from where the melt is ejected under the action of thecentrifugal force. Means for drawing by gas stream and for collecting ona receiving member are also provided.

In order to provide for the assembly of the fibers together and to makeit possible for the web to have cohesion, a sizing compositioncomprising a thermosetting resin is projected onto the fibers, on theroute between the outlet of the centrifugal device and the receivingmember. The web of fibers coated with the size is subjected to a heattreatment, at a temperature generally of greater than 100° C., in orderto bring about the polycondensation of the resin and to thus obtain athermal and/or acoustic insulating product having specific properties,in particular dimensional stability, tensile strength, thicknessrecovery after compression and homogeneous color.

The sizing composition to be projected onto the mineral wool isgenerally provided in the form of an aqueous solution including thethermosetting resin and additives, such as a catalyst for thecrosslinking of the resin, an adhesion-promoting silane, adust-preventing mineral oil, and the like. The sizing composition isgenerally applied to the fibers by spraying.

The properties of the sizing composition depend largely on thecharacteristics of the resin. From the viewpoint of the application, itis necessary for the sizing composition to exhibit good sprayability andto be able to be deposited at the surface of the fibers in order toefficiently bind them.

The resin has to be stable for a given period of time before being usedto form the sizing composition, which composition is generally preparedat the time of use by mixing the resin and the additives mentionedabove.

At the regulatory level, it is necessary for the resin to be regarded asnon-polluting, that is to say for it to comprise—and for it to generateduring the sizing stage or subsequently—as little as possible in the wayof compounds which may be harmful to human health or to the environment.The thermosetting resins most commonly used are phenolic resinsbelonging to the family of the resols. In addition to their goodcrosslinkability under the abovementioned thermal conditions, theseresins are soluble in water, have a good affinity for mineral fibers, inparticular glass fibers, and are relatively inexpensive.

These resols are obtained by condensation of phenol and formaldehyde, inthe presence of a basic catalyst, in a formaldehyde/phenol molar ratioof greater than 1, so as to promote the reaction between the phenol andthe formaldehyde and to reduce the level of residual phenol in theresin. The condensation reaction between the phenol and the formaldehydeis carried out while limiting the degree of condensation of themonomers, in order to avoid the formation of long, relativelywater-insoluble, chains which reduce the dilutability. Consequently, theresin comprises a certain proportion of unreacted monomer, in particularformaldehyde, the presence of which is undesirable because of its knownharmful effects.

For this reason, resol-based resins are generally treated with urea,which reacts with the free formaldehyde by trapping it in the form ofnonvolatile urea-formaldehyde condensates. The presence of urea in theresin in addition brings a certain economic advantage as a result of itslow cost because it is possible to introduce it in a relatively largeamount without affecting the operating qualities of the resin, inparticular without harming the mechanical properties of the finalproduct, which significantly lowers the total cost of the resin.

Nevertheless, it has been observed that, under the temperatureconditions to which the web is subjected in order to obtain crosslinkingof the resin, the urea-formaldehyde condensates are not stable; theydecompose with restoration of the formaldehyde and urea (in its turn atleast partially decomposed to give ammonia) which are released into theatmosphere of the factory.

Regulations with regard to environmental protection, which are becomingmore restrictive, are forcing manufacturers of insulating products tolook for solutions which make it possible to further lower the levels ofundesirable emissions, in particular of formaldehyde.

Solutions in which resols are replaced in sizing compositions are knownand are based on the use of a carboxylic acid polymer, in particular anacrylic acid polymer.

In U.S. Pat. No. 5,340,868, the size comprises a polycarboxylic polymer,a β-hydroxyamide and an at least trifunctional monomeric carboxylicacid.

Provision has been made for sizing compositions comprising apolycarboxylic polymer, a polyol and a catalyst, which catalyst is aphosphorus-comprising catalyst (U.S. Pat. No. 5,318,990, U.S. Pat. No.5,661,213, U.S. Pat. No. 6,331,350, US 2003/0008978), a fluoroborate(U.S. Pat. No. 5,977,232) or else a cyanamide, a dicyanamide or acyanoguanidine (U.S. Pat. No. 5,932,689).

A description has also been given of sizing compositions comprising analkanolamine including at least two hydroxyl groups and a polycarboxylicpolymer (U.S. Pat. No. 6,071,994, U.S. Pat. No. 6,099,773, U.S. Pat. No.6,146,746) in combination with a copolymer (U.S. Pat. No. 6,299,936).

In US 2002/0091185, the polycarboxylic polymer and the polyol are usedin amounts such that the ratio of the number of equivalents of OH groupsto the number of equivalents of COOH groups varies from 0.6/1 to 0.8/1.

In US 2002/0188055, the sizing composition comprises a polycarboxylicpolymer, a polyol and a cationic, amphoteric or nonionic surfactant.

In US 2004/0002567, the sizing composition includes a polycarboxylicpolymer, a polyol and a coupling agent of silane type.

In US 2005/0215153, a description is given of a size formed from aprebinder comprising a carboxylic acid polymer and a polyol, and from adextrin as cobinder.

A description is given, in WO 2006/120523, of a sizing composition whichcomprises (a) a poly(vinyl alcohol), (b) a polyfunctional crosslinkingagent chosen from nonpolymeric polyacids or their salts, the anhydridesand (c) optionally a catalyst, the (a):(b) ratio by weight varying from95:5 to 35:65 and the pH being at least equal to 1.25.

In addition, WO 2008/053332 discloses a sizing composition whichcomprises an adduct (a) of a sugar polymer and (b) of a polyfunctionalcrosslinking agent chosen from monomeric polyacids or their salts, andtheir anhydrides, which is obtained under conditions such that the(a):(b) ratio by weight varies from 95:5 to 35:65.

Mention may be made, among the disadvantages exhibited by the sizingcompositions which have just been mentioned, of the high costs, a highviscosity, a low pH, which causes problems of acid corrosion, and a highcrosslinking temperature.

An aim of the present invention is to provide a sizing composition forinsulating products based on mineral wool which is devoid offormaldehyde, thus making it possible to have available an alternativeto the sizing compositions based on resols.

Another aim is to provide a sizing composition prepared from naturalcompounds resulting from renewable sources, in particular plant sources.

Another aim is to provide a sizing composition which makes it possibleto manufacture insulating products which are white in color.

In order to achieve these aims, the present invention provides a sizingcomposition for insulating products based on mineral wool, in particularon glass or on rock, which comprises:

-   -   at least one hydrogenated sugar, and    -   at least one polyfunctional crosslinking agent.

“Hydrogenated sugar” is understood here to mean all the productsresulting from the reduction, in whatever way, of a sugar chosen frommonosaccharides, oligosaccharides and polysaccharides which are linear,cyclic or branched, and the mixtures of these products, in particularstarch hydrolyzates. The starch hydrolyzates according to the inventionare obtained in a way known per se, for example by enzymatic and/or acidhydrolysis. The degree of hydrolysis of the starch is generallycharacterized by the dextrose equivalent (DE), defined by the followingrelationship:

${DE} = {100 \times \left\lbrack \frac{{number}\mspace{14mu} {of}\mspace{14mu} {glycoside}\mspace{14mu} {bonds}\mspace{14mu} {cleaved}}{{number}\mspace{14mu} {of}\mspace{14mu} {glycoside}\mspace{14mu} {bonds}\mspace{14mu} {in}\mspace{14mu} {the}\mspace{14mu} {starting}\mspace{14mu} {starch}} \right\rbrack}$

The DE of starch hydrolyzates varies according to the method ofhydrolysis used (type of enzyme(s), for example) and the degree ofhydrolysis: the distribution of products with different degrees ofpolymerization can vary within wide limits.

The preferred starch hydrolyzates have a DE of between 5 and 99 andadvantageously between 10 and 80.

The sugar can be hydrogenated by known methods operating underconditions of high hydrogen pressure and high temperature in thepresence of a catalyst chosen from Groups IB, IIB, IVB, VI, VII and VIIIof the Periodic Table of the Elements, preferably from the groupconsisting of nickel, platinum, palladium, cobalt, molybdenum and theirmixtures. The preferred catalyst is Raney nickel. The hydrogenationconverts the sugar or the mixtures of sugars (starch hydrolyzate) to thecorresponding polyols.

Although not being preferred, the hydrogenation can be carried out inthe absence of hydrogenation catalyst, in the presence of a source ofhydrogen other than hydrogen gas, for example an alkali metalborohydride, such as sodium borohydride.

Mention may be made, as examples of hydrogenated sugars, of glycerol,erythritol, arabitol, xylitol, sorbitol, mannitol, iditol, maltitol,isomaltitol, lactitol, cellobitol, palatinitol, maltotritol and theproducts from the hydrogenation of starch hydrolyzates, in particularsold by Roquette under the name Polysorb®. Preferably, use is made ofthe products from the hydrogenation of starch hydrolyzates.

The hydrogenated sugar in accordance with the invention has anumber-average molar mass of less than 100 000, preferably of less than50 000, advantageously of less than 5000 and better still of greaterthan 180. The hydrogenated sugar in accordance with the invention cancomprise reducing sugars in a low proportion which does not exceed 5% byweight (on a dry basis), preferably 1% by weight and better still 0.5%by weight.

The polyfunctional crosslinking agent is capable of reacting with thehydroxyl groups of the hydrogenated sugar under the effect of heat toform acid bonds, which result in a polymeric network being obtained inthe final binder. Said polymer network makes it possible to establishbonds at the junction points of the fibers in the mineral wool.

The polyfunctional crosslinking agent is chosen from organicpolycarboxylic acids or the salts of these acids, the anhydrides and thepolyaldehydes.

“Organic polycarboxylic acid” is understood to mean an organic acidcomprising at least two carboxyl functional groups, preferably at most300 carboxyl functional groups, advantageously at most 70 carboxylfunctional groups and better still at most 15 carboxyl functionalgroups. The organic polycarboxylic acid can be a nonpolymeric orpolymeric acid;

it exhibits a number-average molar mass generally of less than or equalto 50 000, preferably of less than or equal to 10 000 and advantageouslyof less than or equal to 5000.

The nonpolymeric organic polycarboxylic acid is a saturated orunsaturated and linear or branched alicyclic acid, a cyclic acid or anaromatic acid.

The nonpolymeric organic polycarboxylic acid can be a dicarboxylic acid,for example oxalic acid, malonic acid, succinic acid, glutaric acid,adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,malic acid, tartaric acid, tartronic acid, aspartic acid, glutamic acid,fumaric acid, itaconic acid, maleic acid, traumatic acid, camphoricacid, phthalic acid and its derivatives, in particular comprising atleast one boron or chlorine atom, tetrahydrophthalic acid and itsderivatives, in particular comprising at least one chlorine atom, suchas chlorendic acid, isophthalic acid, terephthalic acid, mesaconic acidand citraconic acid; a tricarboxylic acid, for example citric acid,tricarballylic acid, 1,2,4-butane-tricarboxylic acid, aconitic acid,hemimellitic acid, trimellitic acid and trimesic acid; or atetracarboxylic acid, for example 1,2,3,4-butanetetracarboxylic acid andpyromellitic acid.

Mention may be made, as examples of polymeric organic polycarboxylicacids, of homopolymers of unsaturated carboxylic acids, such as(meth)acrylic acid, crotonic acid, isocrotonic acid, maleic acid,cinnamic acid, 2-methylmaleic acid, fumaric acid, itaconic acid,2-methylitaconic acid, α,β-methyleneglutaric acid and unsaturateddicarboxylic acid monoesters, such as C₁-C₁₀ alkyl maleates andfumarates, and copolymers of at least one abovementioned unsaturatedcarboxylic acid and at least one vinyl monomer, such as unsubstitutedstyrene or styrene substituted by alkyl, hydroxyl or sulfonyl groups orby a halogen atom, (meth)acrylonitrile, unsubstituted (meth)acrylamideor (meth)acrylamide substituted by C₁-C₁₀ alkyl groups, alkyl(meth)acrylates, in particular methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl (meth)acrylate and isobutyl (meth)acrylate,glycidyl (meth)acrylate, butadiene and a vinyl ester, in particularvinyl acetate.

Preferably, the sizing composition comprises at least one nonpolymericorganic polycarboxylic acid having a number-average molar mass of lessthan or equal to 1000, preferably of less than or equal to 750 andadvantageously of less than or equal to 500, optionally as a mixturewith at least one polymeric organic acid.

The polyfunctional crosslinking agent can be an anhydride, in particularmaleic anhydride, succinic anhydride or phthalic anhydride. However, theaddition of an anhydride to the sizing composition brings about a majorfault in the pH, which causes problems of corrosion of the equipment inthe line for the manufacture and hydrolysis of the hydrogenated sugar.The introduction of a base makes it possible to bring the pH of thesizing composition to a value sufficient to prevent these problems. Thecost related to the supplementary addition of the base means that theuse of anhydride is not preferred.

The polyfunctional crosslinking agent can also be a polyaldehyde.“Polyaldehyde” is understood to mean an aldehyde comprising at least twoaldehyde functional groups.

Preferably, the polyaldehyde is a nonpolymeric dialdehyde, for exampleglyoxal, glutaraldehyde, 1,6-hexanedial or 1,4-terephthalaldehyde.

Polyaldehydes have a very high reactivity with regard to the hydroxylgroups of the hydrogenated sugar but also to hydroxyl groups in general,which can present disadvantages, in particular a reduction in thestability and/or a pregelling of the sizing composition before thethermal crosslinking treatment. In order to prevent these disadvantages,the aldehyde functional groups of the polyaldehyde are advantageouslymasked, to prevent the reaction with the constituents present in thesizing composition, before the mineral wool enters the oven. Mention maybe made, as example of agent which makes it possible to mask thealdehyde functional groups, of urea and cyclic ureas. In the sizingcomposition, the hydrogenated sugar represents from 10 to 90% of theweight of the mixture composed of hydrogenated sugar and thepolyfunctional crosslinking agent, preferably more than 20%, inparticular from 20 to 85%, advantageously at least 30% and better stillfrom 30 to 80%.

The sizing composition can additionally comprise an acid or basiccatalyst which has in particular the role of adjusting the temperatureat which crosslinking begins.

The catalyst can be chosen from Lewis bases and acids, such as clays,colloidal or noncolloidal silica, organic amines, quaternary amines,metal oxides, metal sulfates, metal chlorides, urea sulfates, ureachlorides and catalysts based on silicates.

The catalyst can also be a phosphorus-comprising compound, for examplean alkali metal hypophosphite salt, an alkali metal phosphite, an alkalimetal polyphosphate, an alkali metal hydrogenphosphate, a phosphoricacid or an alkylphosphonic acid. Preferably, the alkali metal is sodiumor potassium.

The catalyst can also be a compound comprising fluorine and boron, forexample tetrafluoroboric acid or a salt of this acid, in particular analkali metal tetrafluoroborate, such as sodium tetrafluoroborate orpotassium tetrafluoroborate, an alkaline earth metal tetrafluoroborate,such as calcium tetrafluoroborate or magnesium tetrafluoroborate, a zinctetrafluoroborate and an ammonium tetrafluoroborate.

Preferably, the catalyst is sodium hypophosphite, sodium phosphite andthe mixtures of these compounds.

The amount of catalyst introduced into the sizing composition canrepresent up to 20% of the weight of the hydrogenated sugar andpolyfunctional crosslinking agent, preferably up to 10%, andadvantageously is at least equal to 1%. The sizing composition inaccordance with the invention can additionally comprise the conventionaladditives below in the following proportions, calculated on the basis of100 parts by weight of hydrogenated sugar and polyfunctionalcrosslinking agent:

-   -   from 0 to 2 parts of silane, in particular an aminosilane,    -   from 0 to 20 parts of oil, preferably from 4 to 15 parts,    -   from 0 to 5 parts of a hydrophobic agent, in particular        silicone,    -   from 0 to 20 parts of a polyol other than the hydrogenated        sugars,    -   from 0 to 30 parts of urea, preferably from 0 to 20 parts,    -   from 0 to 30 parts of an “extender” chosen from lignin        derivatives, such as ammonium lignosulfonate (ALS) or sodium        lignosulfonate, and animal or plant proteins.

The role of the additives is known and is briefly restated: the silaneis an agent for coupling between the fibers and the binder, and alsoacts as anti-aging agent; the oils are dust-preventing and hydrophobicagents;

the urea acts as plasticizer and in addition makes it possible to adjustthe gel time of the sizing composition, in order to prevent problems ofpregelling; the “extender” is an organic filler, soluble or dispersiblein the sizing composition, which makes it possible in particular toreduce the cost of the latter.

The polyol added as additive is necessarily different from thehydrogenated sugar; in particular, polyols provided in the form ofpolymers comprising nonsaccharide units, such as vinyl alcohol polymersand copolymers, are ruled out.

The sizing composition is prepared by simple mixing of theabovementioned constituents.

The sizing composition obtained exhibits an acidic pH, of the order of 1to 4, which is preferably maintained at a value at least equal to 2,advantageously at least equal to 3, so as to limit problems of corrosionof the line for the manufacture of insulating products based on mineralwool. The pH can be adjusted by adding a base to the sizing composition,in particular a nitrogenous base, such as triethanolamine, or ammoniumhydroxide or sodium hydroxide or potassium hydroxide. When thepolyfunctional crosslinking agent is a nonpolymeric polyacid, it can beadvantageous to subject the sizing composition to a heat treatment, soas to cause a portion of the hydrogenated sugar to react with saidpolyacid. By virtue of this heat treatment, the content of freepolyacids with a low molar mass in the sizing composition is reduced,which has the effect of limiting the gaseous emissions generated duringthe curing of the size in the oven. The heat treatment is carried out ata temperature which can range from 40 to 130° C.

The sizing composition is intended to be applied to mineral fibers, inparticular glass or rock fibers.

Conventionally, the sizing composition is projected onto the mineralfibers at the outlet of the centrifugal device and before they arecollected on the receiving member in the form of a web of fibers whichis subsequently treated at a temperature which makes possible thecrosslinking of the size and the formation of an infusible binder. Thecrosslinking of the size according to the invention takes place at atemperature comparable to that of a conventional formaldehyde-phenolresin, at a temperature of greater than or equal to 110° C., preferablyof greater than or equal to 130° C. and advantageously of greater thanor equal to 140° C.

The acoustic and/or thermal insulating products obtained from thesesized fibers also constitute a subject matter of the present invention.

These products are generally provided in the form of a mat or felt ofmineral wool, of glass or of rock, or also of a veil of mineral fibers,also of glass or of rock, intended in particular to form a surfacecoating on said mat or felt. These products exhibit a particularlyadvantageously white color.

In addition, the insulating products exhibit great resistance to thegrowth of microorganisms, in particular of molds, which is due to thenonfermentable nature of the hydrogenated sugar.

The following examples make it possible to illustrate the inventionwithout, however, limiting it.

In these examples, the following are measured:

-   -   On the sizing composition

the crosslinking start temperature (T_(c)) and the crosslinking rate (R)by the Dynamic Mechanical Analysis (DMA) method, which makes it possibleto characterize the viscoelastic behavior of a polymeric material. Theprocedure is as follows: a sample of Whatman paper is impregnated withthe sizing composition (content of organic solids of the order of 40%)and is then fixed horizontally between two jaws. An oscillatingcomponent equipped with a device for measuring the stress as a functionof the strain applied is positioned on the upper face of the sample. Thedevice makes it possible to calculate the modulus of elasticity E′. Thesample is heated to a temperature varying from 20 to 250° C. at a rateof 4° C./min. The curve of variation in the modulus of elasticity E′ (inMPa) as a function of the temperature (in ° C.) is plotted from themeasurements, the general appearance of the curve being given in FIG. 1.The values corresponding to the crosslinking start temperature (T_(c)),in ° C., and the slope corresponding to the crosslinking rate (R), inMPa/° C., are determined on the curve.

-   -   On the insulating product

the tensile strength according to the standard ASTM C 686-71T on asample cut out by stamping from the insulating product. The sample hasthe shape of a torus with a length of 122 mm, a width of 46 mm, a radiusof curvature of the cut-out of the outer edge equal to 38 mm and aradius of curvature of the cut-out of the inner edge equal to 12.5 mm.

The sample is positioned between two cylindrical mandrels of a testmachine, one of which is movable and is moved at a constant rate. Thebreaking force F (in gram-force) of the sample is measured and thetensile strength TS, defined by the ratio of the breaking force F to theweight of the sample, is calculated.

The tensile strength is measured after manufacture (initial tensilestrength) and after accelerated aging in an autoclave at a temperatureof 105° C. under 100% relative humidity for 15 minutes (TS 15).

-   -   the initial thickness of the insulating product and the        thickness after compressing for 24 hours and 12 days with a        degree of compression (defined as being the ratio of the nominal        thickness to the thickness under compression) equal to 5/1. The        thickness measurements, expressed as %, make it possible to        evaluate the good dimensional behavior of the product.    -   the water absorption under the conditions of the standard EN        1609, expressed as kg of water absorbed per m² of insulating        product. The insulating products for which the water absorption        is less than 1 kg/m² are regarded as having a low short-term        water absorption (24 hours) and belong to the “WS” category        according to the ACERMI certification.    -   the thermal conductivity coefficient λ according to the standard        EN 13162, expressed in W/(m×°K).

EXAMPLES 1 TO 4

Sizing compositions are prepared which comprise the constituentsappearing in Table 1, expressed as parts by weight.

The hydrogenated sugar is the product of the hydrogenation of a starchhydrolysate (solids content: 70%) which comprises 12% by weight ofmaltitol and 12% by weight of sorbitol.

The sizing compositions are prepared by successively introducing, into avessel, the hydrogenated sugar, citric acid and sodium hypophosphite(catalyst) with vigorous stirring until the constituents have completelydissolved.

The properties of the sizing compositions which appear in the followingtable 1 are evaluated in comparison with a conventional sizingcomposition including a formaldehyde-phenol resin and urea (Reference)prepared in accordance with example 2, test 1, of WO 01/96254 A1.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ref. Composition Hydrogenated sugar 5858 58 57 — (Polysorb ® 70/12/12; Roquette) Citric acid 42 42 42 31 —Acrylic homopolymer — — — 12 — (Acusol ® 445; Röhm & Haas Sodiumhypophosphite 5 5 5 5 — Glycerol — 10 — — — Silicone — — 1 — —Properties Crosslinking start temperature 155 153 n.d. 152 151 Tc (° C.)Crosslinking rate R (MPa/° C.) 94 87 n.d. 85 161 Viscosity at 25° C.(mPa · s)⁽¹⁾ 9.0 8.7 n.d. 11.0 8.0 Viscosity at 50° C. (mPa · s)⁽¹⁾ 6.05.9 n.d. 6.7 6.0 ⁽¹⁾solution with a solids content of 40% n.d.: notdetermined

The sizing compositions of examples 1 to 4 have similar properties tothose of the Reference in terms of crosslinking start temperature(T_(c)) and of viscosity. The crosslinking rate (R) remains lower thanthat of the Reference.

The compositions of examples 1 to 4, and also the formaldehyde-phenolresin (Reference), are used to form insulation products based on glasswool.

Glass wool is manufactured by the internal centrifugation technique inwhich the molten glass composition is converted into fibers by means ofa tool, referred to as centrifuging disk, comprising a basket forming achamber for receiving the molten composition and a peripheral bandpierced by a multitude of orifices: the disk is rotated about itsvertically positioned axis of symmetry, the composition is ejectedthrough the orifices under the effect of the centrifugal force and thematerial escaping from the orifices is drawn into fibers with theassistance of a drawing gas stream.

Conventionally, a size spraying ring is positioned beneath thefiberizing disk so as to uniformly distribute the sizing compositionover the glass wool which has just been formed.

The mineral wool, thus sized, is collected on a belt conveyor equippedwith internal extraction boxes which hold the mineral wool in the formof a felt or web at the surface of the conveyor. The conveyorsubsequently moves through an oven maintained at 290° C. where theconstituents of the size polymerize to form a binder. The insulatingproduct obtained exhibits a density of 17.5 kg/m³, a thickness ofapproximately 82 mm immediately after manufacture and a loss on ignitionof the order of 5%. The properties of the insulating products are givenin table 2 below.

TABLE 2 Sizing composition Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ref. Tensile strength(gf/g) Before aging 327 319 258 333 419 After aging 295 269 188 218 351Loss (%) 9.80 15.70 27.10 34.53 16.22 Thickness (mm)  1 hour 83.0 81.783.2 79.6 78.9 24 hours 78.8 77.8 80.2 77.5 77.6 12 days 77.1 75.3 77.076.6 77.0 Water absorption (kg/m²) 8.6 n.d. 0.4 n.d. 2.6 λ (W/(m × ° K)0.0338 0.0339 0.0337 0.0338 0.0336 n.d.: not determined

The insulating products manufactured with the sizing compositions ofexamples 1 to 4 exhibit similar properties to the reference product interms of recovery of thickness after compression for 12 days and ofthermal conductivity coefficient λ. The insulating products treated withthe sizing composition of examples 1 and 2 exhibit a good tensilestrength after aging (loss equal to 9.8 and 15.7% respectively) incomparison with the Reference.

1. A sizing composition for insulating products based on mineral wool,in particular of rock or of glass, the composition comprising: at leastone hydrogenated sugar, and at least one polyfunctional crosslinkingagent.
 2. The composition as claimed in claim 1, wherein thehydrogenated sugar is chosen from monosaccharides, oligosaccharides andpolysaccharides which are linear, cyclic or branched.
 3. The compositionas claimed in claim 1, wherein the hydrogenated sugar is glycerol,erythritol, arabitol, xylitol, sorbitol, mannitol, iditol, maltitol,isomaltitol, lactitol, cellobitol, palatinitol, maltotritol and theproducts from the hydrogenation of starch hydrolyzates.
 4. Thecomposition as claimed in claim 3, wherein the hydrogenated sugar is aproduct from the hydrogenation of starch hydrolyzates.
 5. Thecomposition as claimed in claim 1, wherein the hydrogenated sugarexhibits a number-average molar mass of less than 100 000, preferably ofless than 50 000, advantageously of less than 5000 and better still ofgreater than
 180. 6. The composition as claimed in claim 1, wherein thehydrogenated sugar comprises reducing sugars in a proportion notexceeding 5% by weight (on a dry basis), preferably 1% by weight andbetter still 0.5% by weight.
 7. The composition as claimed in claims 1,wherein the polyfunctional crosslinking agent is chosen from organicpolycarboxylic acids or the salts of these acids, the anhydrides and thepolyaldehydes.
 8. The composition as claimed in claim 7, wherein theorganic polycarboxylic acid comprises at least two carboxyl functionalgroups, preferably at most 300 carboxyl functional groups,advantageously at most 70 carboxyl functional groups and better still atmost 15 carboxyl functional groups.
 9. The composition as claimed inclaim 8, wherein the organic polycarboxylic acid exhibits anumber-average molar mass of less than or equal to 50 000, preferably ofless than or equal to 10 000 and advantageously of less than or equal to5000.
 10. The composition as claimed in claim 7, wherein the organicpolycarboxylic acid is chosen from saturated or unsaturated and linearor branched alicyclic nonpolymeric organic polycarboxylic acids, cyclicacids and aromatic acids.
 11. The composition as claimed in claim 10,wherein the organic polycarboxylic acid is chosen from dicarboxylicacids, in particular oxalic acid, malonic acid, succinic acid, glutaricacid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacicacid, malic acid, tartaric acid, tartronic acid, aspartic acid, glutamicacid, fumaric acid, itaconic acid, maleic acid, traumatic acid,camphoric acid, phthalic acid and its derivatives, in particularcomprising at least one boron or chlorine atom, tetrahydrophthalic acidand its derivatives, in particular comprising at least one chlorineatom, isophthalic acid, terephthalic acid, mesaconic acid and citraconicacid, tricarboxylic acids, in particular citric acid, tricarballylicacid, 1,2,4-butanetricarboxylic acid, aconitic acid, hemimellitic acid,trimellitic acid and trimesic acid, and tetracarboxylic acids, inparticular 1,2,3,4-butanetetracarboxylic acid and pyromellitic acid. 12.The composition as claimed in claims 7, wherein the organicpolycarboxylic acid is chosen from polymeric organic polycarboxylicacids, in particular homopolymers of unsaturated carboxylic acids andcopolymers of at least one unsaturated carboxylic acid and of at leastone vinyl monomer.
 13. The composition as claimed in claim 12, whereinthe unsaturated carboxylic acid is (meth)acrylic acid, crotonic acid,isocrotonic acid, maleic acid, cinnamic acid, 2-methylmaleic acid,fumaric acid, itaconic acid, 2-methylitaconic acid,α,β-methyleneglutaric acid and unsaturated dicarboxylic acid monomers,and the vinyl monomer is unsubstituted styrene or styrene substituted byalkyl, hydroxyl or sulfonyl groups or by a halogen atom,(meth)acrylonitrile, unsubstituted (meth)acrylamide or (meth)acrylamidesubstituted by C₁-C₁₀ alkyl groups, alkyl (meth)acrylates, glycidyl(meth)acrylate, butadiene and a vinyl ester.
 14. The composition asclaimed in claim 7, wherein the anhydride is maleic anhydride, succinicanhydride or phthalic anhyride.
 15. The composition as claimed in claim7, wherein the polyaldehyde is a nonpolymeric dialdehyde, in particularglyoxal, glutaraldehyde, 1,6-hexanedial or 1,4-terephthalaldehyde. 16.The composition as claimed in claim 15, wherein the aldehyde functionalgroups of the polyaldehyde are masked by urea or by cyclic ureas. 17.The composition as claimed in claim 1, wherein the hydrogenated sugarrepresents from 10 to 90% of the weight of the mixture composed ofhydrogenated sugar and the polyfunctional crosslinking agent, preferablyat least 20%, in particular from 20 to 85%, advantageously at least 30%,in particular from 30 to 80%.
 18. The composition as claimed in claim 1,comprising a catalyst chosen from Lewis acids and bases,phosphorus-comprising compounds and compounds comprising fluorine andboron.
 19. The composition as claimed in claim 18, wherein the catalystrepresents up to 20% of the weight of the hydrogenated sugar andpolyfunctional crosslinking agent, preferably up to 10%, andadvantageously at least 1%.
 20. The composition as claimed in claim 1,comprising the additives below in the following proportions, calculatedon the basis of 100 parts by weight of hydrogenated sugar andpolyfunctional crosslinking agent: from 0 to 2 parts of silane, inparticular an aminosilane, from 0 to 20 parts of oil, preferably from 4to 15 parts, from 0 to 5 parts of a hydrophobic agent, in particularsilicone, from 0 to 20 parts of a polyol other than the hydrogenatedsugars, from 0 to 30 parts of urea, preferably from 0 to 20 parts, from0 to 30 parts of an “extender” chosen from lignin derivatives, such asammonium lignosulfate (ALS) or sodium lignosulfate, and animal or plantproteins.
 21. An acoustic and/or thermal insulating product based onmineral wool, in particular of glass or of rock, sized using the sizingcomposition as claimed in claim
 1. 22. A veil of mineral fibers, inparticular of glass or of rock, sized using the sizing composition asclaimed in claim 1.